Since many indicator gauges are used in surroundings which receive very little light, either naturally or artificially, various arrangements have been made to illuminate such gauges so that they can be easily read. Such gauges are generally provided with their own light source for the purpose of the above. Many types of gauges are such constructed that light rays from the light source are directed from radial outside of the dial board to illuminate the indicia of the dial board and the position of the indicator pointer.
In such a conventional indicator gauge, however, the following drawbacks will be encountered especially on the pointer. First, illumination on the pointer changes considerably in accordance with changes of the angular position of the pointer with respect to the dial board. If elimination of this drawback is necessary, a great number of light sources must be arranged around the dial board. Second, generally same illumination effects will occur on the pointer and the dial board because of using common light rays. This will limit the reliability of sure distinction of the pointer from its background that is the face of the dial board. These drawbacks will cause difficulties to arise in clearly and quickly reading the dial.